What does Nominal Impedance mean?

[ozzzy]

What does Nominal Impedance mean?​

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What does Nominal Impedance mean?
I’m trying to decide on some new speakers (Clarisys Minute). They are rated at 86-88 sensitivity and a nominal impedance of 3.5 flat. Although graphs show it about 6 ohms from 20hz-500hz and at 2Khz and above about 3 ohms.
My present speakers, Focal Sopra 2 are rated as 91 sensitivity and 8-ohm nominal impedance, but minimum is 3 ohms.
So, I am presently using Bob Carver 350 amps (rated as 350 Amps/channel 8 ohm and 400 watts /channel 4 ohm) which are tube mono blocks. and I like to crank it up at times!
Can someone explain about Nominal Impedance and if my amp(s) will have a problem driving the Clarisys Minute speakers?

ozzy

 

[Gregadd]

Average impedance over the frequency spectrum.

 

[Bbock]

What does Nominal Impedance mean?​

---

What does Nominal Impedance mean?
I’m trying to decide on some new speakers (Clarisys Minute). They are rated at 86-88 sensitivity and a nominal impedance of 3.5 flat. Although graphs show it about 6 ohms from 20hz-500hz and at 2Khz and above about 3 ohms.
My present speakers, Focal Sopra 2 are rated as 91 sensitivity and 8-ohm nominal impedance, but minimum is 3 ohms.
So, I am presently using Bob Carver 350 amps (rated as 350 Amps/channel 8 ohm and 400 watts /channel 4 ohm) which are tube mono blocks. and I like to crank it up at times!
Can someone explain about Nominal Impedance and if my amp(s) will have a problem driving the Clarisys Minute speakers?

ozzy

FYI, The Clarisys web site says nominal impedance of the Minuets are 4.25 ohms.

 

[DeadWax]

Average impedance over the frequency spectrum.

I've always wondered whether manufacturers actually calculate the average (eg best fit analysis) or they are just eyeballing and perhaps even tipping the spec towards their marketing aspiration. It's also important to understand where in the frequency range the amp is seeing the most challenging load, and not just reflect on the "nominal" number.

 

[ozzzy]

Suncost Audio says they are 3.5 ohm flat, and they did a measurement on them.

ozzy

 

[ozzzy]

Jim Clark from Carver just replied to my email saying that the Carver amps would have no problem driving the speaker based on the specs in this posting. But I wish he had provided more detail.

Here is his reply,
"The nominal impedance is an average of the impedance curve. Many speakers vary between 2 and 20 ohms at various frequencies. Your 350's should have no problem driving them. Enjoy! Thanks, Jim"

ozzy

 

[Gregadd]

I've always wondered whether manufacturers actually calculate the average (eg best fit analysis) or they are just eyeballing and perhaps even tipping the spec towards their marketing aspiration. It's also important to understand where in the frequency range the amp is seeing the most challenging load, and not just reflect on the "nominal" number.

It could be that they throw out the two extremes.

 

[Alrainbow]

Imp curves matter more but a relatively flat imp as sun coast says is very good for amp picking. Senn rating of 86 to 88 is a good number , is there any rating for efficiency given.
the panels for most users are not setup to be direct at us so efficiency rating is a better indicator of amp size.
3.5 imp is good things get tougher below 2ohms. what suncoast says I trust he sells entire packages so must know.

 

[Robh3606]

Can someone explain about Nominal Impedance and if my amp(s) will have a problem driving the Clarisys Minute speakers?

You should look at phase as well. The combination of phase angle and impedance is what determines the actual load the amp see's

Rob

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